Encapsulation systems represent an important field of interest for the flavour industry. Encapsulated systems are designed to achieve two kinds of objectives.
The first goal relates to the function of protecting the ingredients entrapped in such systems. In fact, these systems must be capable of protecting an active material encapsulated therein from different kinds of retrogradation and at the same time of preventing the escape of the active material, especially of volatile flavouring component(s). Oxidation of flavours, such as essential oils, resulting in off-notes, poses serious problems for the food industry. Carbohydrates as a class offer a food-acceptable substrate in which volatiles and aromatics have been encapsulated with a certain degree of success. However most water-soluble carbohydrates are hygroscopic and will not reliably hold the encapsulate for long periods. The stabilisation of encapsulation systems therefore remains a critical issue in the field.
Another objective, that is always targeted for an encapsulated system, is to control (depending on the final application) the release of the active ingredient. In particular, if the active is volatile, it is generally of much importance to effectively prevent its release during storage, but at the same time to ensure that the encapsulation system will release the volatile active ingredient during use, triggered by conditions that are typical of such use.
A considerable amount of work has been performed relating to flavouring orally consumed compositions such as chewing gum, chewable medicinal tablets, chewing tobacco and toothpaste, whereby such orally consumed substances produce a flavour impact both initially and over an extended period of time. Problems have arisen in attempting to create encapsulates wherein part of the flavour is released immediately during e.g. mastication, whereas another part provides a sustained release of such flavour.
It is well known that the chewing gum base acts as a ‘sink’ for the added non-encapsulated flavour. In fact, the addition of non-encapsulated flavours to gum bases, as is still conventionally practised in the field, results in the release of only 20-40% of the total flavour during consumption, while the rest remains entrapped in the gum base. Moreover, chewing gums presently on the market have the following problems: (1) 1.0% or more of expensive flavour oil is required to obtain acceptable initial flavour perception (10 times that required in other confections) due to the fact that flavour oils have a great affinity for the chewing gum base, become locked in, and are thus not perceptible, as shown by analysis of cud after 4 hours of chewing wherein 80% of the added flavour still remains; and (2) even at 1.0% or more flavour oil levels, acceptable perception levels last only about 2-3 minutes.
Instead of simply adding flavour ingredients as such to gum bases, encapsulation in colloids such as gum arabic, maltodextrin or proteins has been proposed in the art as an alternative route to improve the efficient delivery of flavour.
U.S. Pat. No. 1,526,039, for example, teaches that if an essential oil or flavouring is combined with chewing gum base in a finely divided condition, and the particles of the flavouring or oil are encased in a suitable matrix so as to prevent contact with the gum base during manufacture, the deleterious effect of this contact on the flavour properties of the gum is thus prevented or largely reduced. By preparing an emulsion of the essential oil and an emulsifying material, which includes e.g. common gums and gelatine, the essential oil is divided into fine particles and these particles are encased in the emulsifying material, so that when the emulsion is added to the gum mass, the essential oil is prevented from coming into direct contact with the base. The physical form of these particles and the properties of the ingredients prevent the control of the flavour release and intensity.
U.S. Pat. No. 2,886,440 teaches a method of preparing a chewing gum characterised by “extended flavour perception time” and high degree of flavour release by incorporating therein a spray-dried composition comprising a volatile, water-immiscible flavouring agent encapsulated within finely divided particles of gelatine, and substantially uniformly distributing said gelatine encapsulated flavouring agent within an all-enveloping mass of a chewable gum base. The use of separate “fixed” and “unfixed” flavour portions is also taught.
U.S. Pat. No. 2,886,446 teaches a chewing gum comprising (i) smaller particles of gelatine characterised by fast release of flavour and (ii) larger particles of gelatine characterised by slower release of flavour, each of the gelatine particles containing dispersed therein, in dried emulsion form, discrete micro-droplets of a volatile water-immiscible flavouring agent, and an all-enveloping mass of a chewable gum base within which the particles are substantially uniformly distributed whereby the flavour is released substantially evenly and uniformly over the extended chewing time. This document further discloses that the grade, type or bloom strength may vary widely. When a rapid release is desired it is preferred to use a gelatine having a Bloom less than 50. When slower release is desired the Bloom preferably will be above 200, according to U.S. Pat. No. 2,886,446.
In U.S. Pat. No. 4,386,106 controlled, delayed release encapsulated flavour particles are disclosed comprising a base powder of partially hydrophilic and slowly soluble material, e.g. a combination of gelatine with gum arabic and a plasticizer such as glycerol, which entraps the flavour and a coating material that is insoluble in but has affinity for the chewing gum base. The essential features of these encapsulates are: (I) the core matrix which entraps and prevents loss of the volatile flavour component during drying and yet which is partially hydrophilic to give quick and sustained release of flavour; and (II) the water insoluble coating which delays flavour release and prevents the flavour from dissolving, and thereby being indefinitely entrapped, in a chewing gum base. The time of flavour release can be controlled by varying parameters such as particle size, the choice of flavour, the bloom strength of the gelatine used in the base matrix, as well as the use of other components in the matrix, such as maltodextrin and/or gum arabic, the amount of water insoluble coating and by treating the outer surface of the base powder matrix to seal and insolubilize the outer surface thereof, e.g. by the use of cross-linking agents.
U.S. Pat. No. 5,116,627 discloses chewing gum compositions comprising a chewing gum base having dispersed therein sweetener-bearing polymeric particles and/or flavour-bearing polymeric particles, which polymeric particles comprise a water-soluble polymer and a water-insoluble polymer being physically associated with each other and in such a manner that one is in the form of discrete entities in a matrix of the other. The active ingredient, e.g. a flavour oil, is incorporated in either or both of the water-soluble and the water-insoluble polymer. The particle size and relative ratio of water-soluble to water-insoluble polymer can be varied to release a lesser proportion of the flavour and/or sweetener composition during mastication initially and a greater quantity on continuous mastication of the chewing gum.
In WO 91/17821 microcapsules containing a flavour component embedded in a matrix material comprising a colloid, such as a gum, modified starch, gelatine, or a dextrine; and optionally saccharides and waxes are disclosed. The wax can be added in order to extend the release of flavour from the matrix, and is preferably a relatively hard, water-insoluble wax. These microcapsules are suitable for use in confectionery products such as chewing gum.
US 2003/082272 discloses a method of preparing water insoluble gel beads consisting of a porous alginate matrix containing entrapped flavour solvent, such as fat or vegetable oil. The beads are loaded with flavour by mixing a liquid flavour with the particles. Since alginate gels have relatively large pores, other macromolecules may be added as a filler material. Suitable filler materials according to US 2003/082272 include dextrins, gums, cellulose derivatives and proteins such as gelatine. Beads having a matrix comprised of approximately 6.5 wt % of gelatine, 6.5 wt % of alginate and 82.5% of miglyol are disclosed in this document.
In spite of all prior-art attempts to provide satisfying controlled-release flavouring compositions as mentioned above there is thus still a need for improved flavouring compositions for use in orally consumed compositions, particularly in chewing gum, which are capable of further extending the satisfactory chewing time thereof, and/or which require the use of less flavouring.